Anti-microbial peptides and method for designing novel anti-microbial peptides

ABSTRACT

Disclosed herein are novel anti-microbial peptides with inhibitory activity against M. tuberculosis and streptococcus bacteria. Additionally, a method for designing novel anti-microbial peptides is disclosed.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a continuation of U.S. Non-Provisional patentapplication Ser. No. 15/259,942, filed Sep. 8, 2016, which is aContinuation-In-Part application of International Application No.PCT/US2015/019761, filed on Mar. 10, 2015, and published as WO2015/138494 A1 on Sep. 17, 2015, which claims the benefit of U.S.Provisional Patent Application Ser. No. 61/950,265, filed on Mar. 10,2014. The contents of each of the prior applications are herebyincorporated by reference herein in their entirety.

STATEMENT ON FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

This invention was made with government support under NIH Grant NumbersR01AI063499 and T32GM067545 awarded by the National Institutes of Healthand NSF Grant Number EAGER (CBET 1122780) awarded by the NationalScience Foundation. The government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates to anti-microbial peptides with inhibitoryactivity against M. tuberculosis and streptococcus bacteria. Thisinvention also relates to a method for designing novel anti-microbialpeptides.

BACKGROUND OF THE INVENTION

Antibiotic resistance is increasing at an alarming rate, especially forthe drug resistant form of Mycobacterium tuberculosis which killed anestimated 170,000 people in 2012 according to the U.S. Centers forDisease Control and Prevention. Alternatives to traditional antibioticsare urgently needed to combat these resistant bacteria. Disruptingbacterial, but not mammalian, outer membrane integrity with peptides isone such strategy to destroy pathogenic bacteria in a highly selectivemanner. Design strategies to develop potent, stable antimicrobialpeptides (“AMPs”) are urgently needed.

AMPs are typically short, cationic peptides that usually adopt an alphahelical conformation. Upon discovery of naturally-occurring AMPs, manywere tested for activity against M. tuberculosis including human andrabbit defensins and porcine protegrins. The most potent of thesedisplayed >90% killing of M. tuberculosis at 50 μg/mL and acted by amechanism which produced visible lesions on the mycobacterial outermembrane. Subsequently, several of the broadly active natural peptideswere modified and tested against M. tuberculosis with minimum inhibitoryconcentrations (“MICs”) as low as 10 μM. Large, entirely syntheticlibraries were also tested against M. tuberculosis with MICs reported aslow as 1 μM. In addition, peptoids, which are more resistant todegradation than peptides, were developed with MIC values as low as 6μM.

Despite clear evidence of their efficacy, the mechanism of action ofAMPs remains debated, though it is believed that the majority of AMPsact through disruption of microbial membranes. Recently, many insightshave been gained into the motifs that govern the effectiveness of shortalpha helical AMPs. The three main parameters that guide effectivenessare peptide hydrophobicity, peptide charge and the distribution ofcharged and hydrophobic residues. Activity is dependent on a mixture ofhydrophobic and cationic residues, arranged to form an amphipathicpeptide.

It has been proposed that the cationic portion targets the peptide tothe negatively charged bacterial membrane, while the hydrophobic portionallows for intercalation into the membrane and subsequent disruption ofthe membrane via a number of proposed mechanisms. This amphipathiccharacter lends itself to design due to the periodicity of the alphahelical arrangement. Peptides can be visualized in two dimensions usinghelical wheel diagrams and sequences bearing separate cationic andhydrophobic faces can be designed.

The majority of prior studies have focused on either optimizingnaturally-occurring peptides or screening large random syntheticlibraries to develop potential drug candidates against a specificmicrobial target or investigating the general mechanism of action. Wehave developed a novel method for designing a novel peptide that usesbioinformatics and rational design informed by known mechanistic rules,to develop a set of more potent initial peptides than those found innature while avoiding the need to screen large randomly constructedlibraries. Specifically, we have combined a de novo design approachcalled Database Filtering with protein engineering, rational design, andthree dimensional (“3-D”) modeling to design potent AMPs against aselected microbial target. Database Filtering uses a library of peptideswith reported activity against the bacterium of choice to determine acharacteristic peptide length, overall charge and hydrophobicity, andcommonly occurring residues, resulting in a set of amino acids. Ourmethod then employs rational design including the use of helical wheeldiagrams to arrange the set of amino acids in a way that maximizes theamphipathic nature of the peptide. 3-D modeling is then employed toverify an alpha-helical conformation and proper distribution of aminoacids to generate the amphipathic surface.

We've successfully used our novel method to design novel AMPs whichdemonstrated high potency against M. tuberculosis and other microbes,such as streptococcus bacteria.

SUMMARY OF THE INVENTION

The present invention relates to an isolated peptide comprising asequence X₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃ (SEQ ID NO: 6), wherein X₁, X₂,X₄, X₆, and X_(ii) are each a hydrophobic amino acid, wherein X₃ isselected from the group consisting of S, T, N, and Q, wherein X₅, X₁₂,and X₁₃ are each a cationic amino acid, wherein X₇, X₈, X₉, and X₁₀ areselected from the group consisting of a hydrophobic amino acid and acationic amino acid, wherein X₇ and X₈ cannot both be a hydrophobicamino acid and cannot both be a cationic amino acid, and wherein X₉ andX₁₀ cannot both be a hydrophobic amino acid and cannot both be acationic amino acid.

In another embodiment, the present invention relates to an isolatedpeptide comprising a sequence ILSLRWX₇X₈X₉X₁₀WKK (SEQ ID NO: 5), whereinX₇ and X₈ are selected from the group consisting of R and W, wherein X₇and X₈ are not the same, and wherein X₉ and X₁₀ are selected from thegroup consisting of K and W, wherein X₉ and X₁₀ are not the same.

In another embodiment, the present invention relates to an isolatedpeptide comprising a sequence ILSLRWRWKWWKK (SEQ ID NO: 1).

In another embodiment, the present invention relates to an isolatedpeptide of claim 1 comprising a sequence ILSLRWWRKWWKK (SEQ ID NO: 2).

In another embodiment, the present invention relates to an isolatedpeptide of claim 1 comprising a sequence ILSLRWRWWKWKK (SEQ ID NO: 3).

In another embodiment, the present invention relates to an isolatedpeptide comprising a sequence IRKLKSWKWLRWL (SEQ ID NO: 4).

In another embodiment, the present invention relates to nucleic acidsencoding the peptides of the invention.

The peptides of the invention, which inhibit M. tuberculosis andstreptococcus bacteria, find utility in the treatment of and preventionof tuberculosis infection, tuberculosis disease, and streptococcalinfections.

Accordingly, in another embodiment, the present invention relates tocompositions comprising at least one of the disclosed peptides, whereinthe composition may include a pharmaceutically acceptable buffer,diluent, carrier, adjuvant, or excipient. These compositions may alsoinclude at least one antibiotic agent.

In another embodiment, the present invention relates to a method fortreating or preventing a microbial infection in or on a subject in needthereof, the method comprising administering to the subject atherapeutically effective amount of at least one of the disclosedpeptides, optionally also administering to the subject at least oneantibiotic agent, wherein the antibiotic agent is administeredsimultaneously or sequentially with the disclosed peptide.

In another embodiment, the present invention relates to a method ofdisinfecting a surface of an article, the method comprising applying tothe surface of the article a composition comprising at least one of thedisclosed peptides.

In another embodiment, the present invention relates to a disinfectingsolution comprising at least one of the disclosed peptides and anacceptable carrier.

In yet another embodiment, the present invention relates to a method fordesigning a novel peptide, the method comprising:

-   -   (a) identifying a set of anti-microbial peptides having        inhibitory activity against a chosen microbe;    -   (b) determining most common length of the anti-microbial        peptides within the set;    -   (c) determining most common net charge of the anti-microbial        peptides within the set;    -   (d) determining most common range of hydrophobicity of the        anti-microbial peptides within the set;    -   (e) determining most common amino acids of the anti-microbial        peptides within the set;    -   (f) optionally, determining at least one common motif present in        the anti-microbial peptides within the set, wherein steps (b)        through (e) and the optional step (f) are performed        sequentially, non-sequentially, or simultaneously;    -   (g) designing an amino acid sequence of the novel peptide by        selecting amino acids of the novel peptide using a helical wheel        diagram, wherein the novel peptide has the most common length        determined in step (b), has the most common net charge        determined in step (c), has the most common hydrophobicity        determined in step (d), consists of the most common amino acids        determined in step (e), and, optionally, has the at least one        common motif determined in step (f), wherein the novel peptide        has one or more hydrophobic faces and one or more hydrophilic        faces as predicted by the helical wheel diagram, wherein at        least one hydrophobic face of the one or more hydrophobic faces        includes at least one hydrophobic face interruption, wherein the        at least one hydrophobic face interruption is positioned within        the at least one hydrophobic face and consists of one or two        amino acids selected from the group consisting of K, R, H, S, T,        N, Q, and combinations thereof;    -   (h) employing a software program to generate a three dimensional        model of the novel peptide having the amino acid sequence        designed in step (g);    -   (i) confirming that the three dimensional model of the novel        peptide generated in step (h) has an alpha helical structure;    -   (j) confirming that the three dimensional model of the novel        peptide generated in step (h) has the one or more hydrophobic        faces and the one or more hydrophilic faces, wherein steps (i)        and (j) are performed sequentially, non-sequentially, or        simultaneously;    -   (k) repeating steps (g) through (j) if the three dimensional        model generated in step (h) does not have an alpha helical        structure, does not have the one or more hydrophobic faces, or        does not have the one or more hydrophilic faces.

The method of the invention has utility in designing novelanti-microbial peptides.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an example of the process of database analysis byidentifying a set of anti-microbial peptides having inhibitory activityagainst M. tuberculosis (“Database creation” step), determining mostcommon length of the anti-microbial peptides within the set (“Peptidelength” step), determining most common net charge of the anti-microbialpeptides within the set (“Charge” step), determining most common rangeof hydrophobicity of the anti-microbial peptides within the set(“Hydrophobicity” step), determining most common amino acids of theanti-microbial peptides within the set (in this example, performedduring “Charge,” “Hydrophobicity,” and “Remaining” steps).

FIG. 2 illustrates use of a helical wheel diagram in designing an aminoacid sequence of peptides B1 through B4. Charged (i.e., cationic) aminoacids are depicted using white circles, polar amino acid S is depictedusing a shaded triangle, and hydrophobic amino acids are depicted usingblack squares. The helical wheel diagrams demonstrate amphipathic natureof peptides B1 through B3. Specifically, the helical wheel diagram ofpeptide B1 shows: (a) a hydrophobic face made up of amino acids I1, W8,L4, and W11; (b) a second hydrophobic face made up of amino acids L2,W6, and W10 with a hydrophobic face interruption by amino acid K13; and(c) a hydrophilic face made up of amino acids K9, R5, and K12 (thenumber after amino acid letter designates the position of that aminoacid). The helical wheel diagram of peptide B2 shows: (a) a hydrophobicface made up of amino acids L4, W11, W7, W10, and W6 with a hydrophobicface interruption by amino acid S3; and (b) a hydrophilic face made upof amino acids K13, K9, R5, K12, and R8 with interruptions byhydrophobic amino acids L2 and I1. The helical wheel diagram of peptideB3 shows: (a) a hydrophobic face made up of amino acids L2, W9, I1, W8,L4, and W11, with a hydrophobic face interruption by amino acids R5 andK12; and (b) a hydrophilic face made up of amino acids R7, S3, K10, andK13 with an interruption by a hydrophobic amino acid W6.

FIG. 3 illustrates minimum inhibitory concentrations (“MICs”) ofpeptides B1 through B4 against attenuated mycobacterium strains. MICswere determined against two differently attenuated M. tuberculosisstrains (MC2 6020 and MC2 6230), M. smegmatis, and attenuated M. bovis(“BCG”). On a molar basis, B3 was equally effective compared with thepositive control, gentamycin (“Gent”), for M. tuberculosis MC2 6020. Ingeneral, the peptides were most effective against M. tuberculosis MC26020, but still remained potent against all tested mycobacteriumstrains. The MIC for B4 against M. smegmatis was not determined.

FIG. 4 illustrates MICs of peptides B1 through B4 against clinicallyrelevant Gram-positive bacteria. MICs were determined against the sixGram-positive bacteria given in the legend. The designed peptides provedvery effective against B. subtilis and various strains of streptococcus.The MIC for B4 against B. subtilis was not determined.

FIG. 5 illustrates MICs of peptides B1 through B4 against clinicallyrelevant Gram-negative bacteria. MICs were determined against the threeGram-negative bacteria given in the legend. Out of the Gram-negativebacteria, the designed peptides proved most effective against E. coli.The designed peptides successfully inhibited the growth of allGram-negative bacteria tested.

FIG. 6 illustrates cytotoxicity of peptides B1 through B4 againstMammalian Macrophage J774.16 Cells. There was no observable cytotoxicityat 34 μM peptide concentration. 20% cell death was observed for peptideB2 at 170 μM, while 40% cell death resulted from peptide B3 incubationat 170 μM, both toxic above the value of the negative control (10%).Still, the peptides have minimal cytotoxicity against macrophage J774.16cells even at higher concentrations.

FIG. 7 illustrates cytotoxicity of peptides B1 through B4 againstMammalian Lung Epithelial Cells. There was no observable cytotoxicity at34 μM peptide concentration. Slight cytotoxicity was seen for peptidesB2 and B3 at 170 μM peptide concentration compared with the negativecontrol.

DETAILED DESCRIPTION OF THE INVENTION

The invention relates to an isolated peptide comprising a sequenceX₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃ (SEQ ID NO: 6), wherein X₁, X₂, X₄, X₆,and X₁₁ are each a hydrophobic amino acid, wherein X₃ is selected fromthe group consisting of S, T, N, and Q, wherein X₅, X₁₂, and X₁₃ areeach a cationic amino acid, wherein X₇, X₈, X₉, and X₁₀ are selectedfrom the group consisting of a hydrophobic amino acid and a cationicamino acid, wherein X₇ and X₈ cannot both be a hydrophobic amino acidand cannot both be a cationic amino acid, and wherein X₉ and X₁₀ cannotboth be a hydrophobic amino acid and cannot both be a cationic aminoacid.

In one embodiment, X₇ and X₈ are selected from the group consisting of Rand W, wherein X₇ and X₈ are not the same. In another embodiment, X₉ andX₁₀ are selected from the group consisting of K and W, wherein X₉ andX₁₀ are not the same. In another embodiment, X₁, X₂, X₄, X₆, and X_(ii)are selected from the group consisting of I, L, and W.

In one embodiment, X₃ is S or T, and preferably S. In one preferredembodiment, X₅, X₁₂, and X₁₃ are selected from the group consisting of Kand R.

The invention also relates to an isolated peptide comprising a sequenceILSLRWX₇X₈X₉X₁₀WKK (SEQ ID NO: 5), wherein X₇ and X₈ are selected fromthe group consisting of R and W, wherein X₇ and X₈ are not the same, andwherein X₉ and X₁₀ are selected from the group consisting of K and W,wherein X₉ and X₁₀ are not the same.

The invention also relates to an isolated peptide of comprising asequence ILSLRWRWKWWKK (SEQ ID NO: 1), the isolated peptide comprising asequence ILSLRWWRKWWKK (SEQ ID NO: 2), the isolated peptide comprising asequence ILSLRWRWWKWKK (SEQ ID NO: 3), and an isolated peptidecomprising a sequence IRKLKSWKWLRWL (SEQ ID NO: 4).

In one embodiment, any peptide of the invention comprises at least oneD-amino acid.

Furthermore, the peptides of the invention may have at least onemodification selected from modification at the C-terminal part byamidation or esterification and modification at the N-terminal part byacylation, acetylation, myristoylation, PEGylation, alkylation,palmitoylation, and the like. The modification may also be halogenation.The halogenation may typically be a halogenation of a Trp side chain.

Further, any amino acid residue of the peptides of the invention maycomprise an amino acid having at least one protecting group. Theprotecting groups may comprise Boc, But, Fmoc, be or any otherprotecting group. A protected amino acid is an amino acid with one ormore of its reactive groups modified with an inert molecule, to reduceand/or prevent chemical reactions of the reactive group.

In another embodiment, the invention relates to a composition comprisingat least one peptide of the invention and a pharmaceutically acceptablebuffer, diluent, carrier, adjuvant, or excipient. This composition mayfurther comprise at least one antibiotic agent.

The antibiotic agent may be selected from the group consisting ofisoniazid, rifampicin, pyrazinamide, ethambutol, levofloxacin,moxifloxacin, ofloxacin, kanamycin, amikacin, capreomycin, streptomycin,bedaquiline, para-aminoslicyclic acid, cycloserine, penicillin,amoxicillin, azithromycin, clarithromycin, erythromycin, cephalosporin,and combinations thereof.

The invention also relates to a method for treating or preventing amicrobial infection in or on a subject in need thereof, the methodcomprising administering to the subject a therapeutically effectiveamount of at least one peptide of the invention. This method may furthercomprise administering to the subject at least one antibiotic agent,wherein the antibiotic agent is administered simultaneously orsequentially with the at least one peptide of the invention. The subjectmay be a mammal.

The microbial infection may be a tuberculosis infection or atuberculosis disease. In this case, the co-administered antibiotic agentmay be selected from the group consisting of isoniazid, rifampicin,pyrazinamide, ethambutol, levofloxacin, moxifloxacin, ofloxacin,kanamycin, amikacin, capreomycin, streptomycin, bedaquiline,para-aminoslicyclic acid, cycloserine, and combinations thereof.

Additionally, the microbial infection may be a streptococcal infection.In this case, the co-administered antibiotic agent may be selected fromthe group consisting of penicillin, amoxicillin, azithromycin,clarithromycin, erythromycin, cephalosporin, and combinations thereof.

Streptococcal infection may be strep throat, scarlet fever, impetigo,toxic shock syndrome, cellulitis and necrotizing fasciitis (flesh-eatingdisease), blood infections, pneumonia and meningitis.

The above methods for treating or preventing a microbial infection mayfurther comprise administering the peptide in the form of a compositioncomprising the peptide and a pharmaceutically acceptable buffer,diluent, carrier, adjuvant, or excipient.

The invention also relates to a method of disinfecting a surface of anarticle, the method comprising applying to the surface of the article acomposition comprising at least one of the peptides of the invention.Such article may be clothes (e.g., clothes of healthcare workers ormilitary personnel), walls (e.g., walls in hospital rooms), or particlesintended for release into the air to kill or reduce pathogens.

The invention also relates to a disinfecting solution comprising atleast one peptide of the invention and an acceptable carrier.

The invention also relates to a method for designing a novel peptide,the method comprising: (a) identifying a set of anti-microbial peptideshaving inhibitory activity against a chosen microbe; (b) determiningmost common length of the anti-microbial peptides within the set; (c)determining most common net charge of the anti-microbial peptides withinthe set; (d) determining most common range of hydrophobicity of theanti-microbial peptides within the set; (e) determining most commonamino acids of the anti-microbial peptides within the set, (f)optionally, determining at least one common motif present in theanti-microbial peptides within the set, wherein steps (b) through (e)and the optional step (f) are performed sequentially, non-sequentially,or simultaneously; (g) designing an amino acid sequence of the novelpeptide by selecting amino acids of the novel peptide using a helicalwheel diagram, wherein the novel peptide has the most common lengthdetermined in step (b), has the most common net charge determined instep (c), has the most common hydrophobicity determined in step (d),consists of the most common amino acids determined in step (e), and,optionally, has the at least one common motif determined in step (f),wherein the novel peptide has one or more hydrophobic faces and one ormore hydrophilic faces as predicted by the helical wheel diagram,wherein at least one hydrophobic face of the one or more hydrophobicfaces includes at least one hydrophobic face interruption, wherein theat least one hydrophobic face interruption is positioned within the atleast one hydrophobic face and consists of one or two amino acidsselected from the group consisting of K, R, H, S, T, N, Q, andcombinations thereof, (h) employing a software program to generate athree dimensional model of the novel peptide having the amino acidsequence designed in step (g); (i) confirming that the three dimensionalmodel of the novel peptide generated in step (h) has an alpha helicalstructure; (j) confirming that the three dimensional model of the novelpeptide generated in step (h) has the one or more hydrophobic faces andthe one or more hydrophilic faces, wherein steps (i) and (j) areperformed sequentially, non-sequentially, or simultaneously; (k)repeating steps (g) through (j) if the three dimensional model generatedin step (h) does not have an alpha helical structure, does not have theone or more hydrophobic faces, or does not have the one or morehydrophilic faces.

In this method for designing the novel peptide, the amino acid sequenceof the novel peptide may have a cationic amino acid at least oneterminus.

The invention also relates to the above method for designing the novelpeptide, further comprising synthesizing the novel peptide. This methodmay further comprise testing the novel peptide for anti-microbialproperties.

The antimicrobial peptides may be synthesized by standard chemicalmethods, including synthesis by automated procedure. In general, peptideanalogues are synthesized based on the standard solid-phase Fmocprotection strategy with HATU(N-[DIMETHYLAMINO-1H-1.2.3.-TRIAZOLO[4,5-B]PYRIDIN-1-YLMETHYLELE]-N-METHY-LMETHANAMINIUMHEXAFLUOROPHOSPHATE N-OXIDE) as the coupling agent or other couplingagents such as HOAt-1-HYDROXY-7-AZABENZOTRIAZOLE. The peptide is cleavedfrom the solid-phase resin with trifluoroacetic acid containingappropriate scavengers, which also deprotects side chain functionalgroups. Crude peptide is further purified using preparativereversed-phase chromatography. Other purification methods, such aspartition chromatography, gel filtration, gel electrophoresis, orion-exchange chromatography may be used. Other synthesis techniques,known in the art, such as the tBoc protection strategy, or use ofdifferent coupling reagents or the like can be employed to produceequivalent peptides.

Peptides may alternatively be synthesized by recombinant production (seee.g., U.S. Pat. No. 5,593,866). A variety of host systems are suitablefor production of the peptide analogues, including bacteria, such as E.coli, yeast, such as Saccharomyces cerevisiae or pichia, insects, suchas Sf9, and mammalian cells, such as CHO or COS-7. There are manyexpression vectors available to be used for each of the hosts and theinvention is not limited to any of them as long as the vector and hostis able to produce the antimicrobial peptide. Vectors and procedures forcloning and expression in E. coli can be found in for example Sambrooket al. (Molecular Cloning: A Laboratory Manual, Cold Spring HarborLaboratory Press, Cold Spring Harbor, N.Y., 1987) and Ausubel et al.(Current Protocols in Molecular Biology, Greene Publishing Co., 1995).

In one preferred embodiment, the most common length of theanti-microbial peptides within the set is 11, 12, 13, 14, or 15,preferably 13, amino acids. In another preferred embodiment, the mostcommon length of the anti-microbial peptides within the set is 24, 25,26, 27, or 28, preferably 26 amino acids.

In general the terms and phrases used herein have their art-recognizedmeaning, which can be found by reference to standard texts, journalreferences and contexts known to those skilled in the art. The followingdefinitions are provided to clarify their specific use in the context ofthe invention.

When used herein, the term “amino acid” is intended to refer to anynatural or unnatural amino acid, whether made naturally orsynthetically, including any such in L- or D-configuration. The term canalso encompass amino acid analog compounds used in peptidomimetics or inpeptoids. The term can include a modified or unusual amino acid or asynthetic derivative of an amino acid, e.g., diamino butyric acid anddiamino propionic acid and the like. Naturally occurring alpha aminoacids are preferred.

The following amino acid name abbreviations are used herein: A or Alafor Alanine; M or Met for Methionine; C or Cys for Cysteine; D or Aspfor Aspartic Acid; E or Glu for Glutamic Acid; F or Phe forPhenylalanine; G or Gly for Glycine; H or His for Histidine; I or Ilefor Isoleucine; K or Lys for Lysine; L or Leu for Leucine; N or Asn forAsparagine; P or Pro for Proline; Q or Glu for Glutamine; R or Arg forArginine; S or Ser for Serine; T or Thr for Threonine; V or Val forValine; W or Trp for Tryptophan; and Y or Tyr for Tyrosine.

The antimicrobial peptides of the invention are composed of amino acidslinked together by peptide bonds. The peptides are in general in alphahelical conformation under hydrophobic conditions. Sequences areconventionally given from the amino terminus to the carboxyl terminus.Unless otherwise noted, the amino acids are L-amino acids. When all theamino acids are of L-configuration, the peptide is said to be anL-enantiomer. When all the amino acids are of D-configuration, thepeptide is said to be a D-enantiomer.

The term “minimum inhibitory concentration” (MIC) refers to the lowestconcentration of an antimicrobial agent (e.g., a peptide) required toprevent growth or otherwise modify a function of a microorganism undercertain conditions, for example in liquid broth medium, and can bedetermined for a number of different microorganisms according tostandard techniques well known in the art.

The term “antimicrobial activity” refers to the ability of a peptide ofthe present invention to modify a function or metabolic process of atarget microorganism, for example so as to at least partially affectreplication, vegetative growth, toxin production, survival, viability ina quiescent state, or other attribute. In an embodiment, the termrelates to inhibition of growth of a microorganism. In a particularembodiment, antimicrobial activity relates to the ability of aninventive peptide to kill at least one bacterial species. In aparticular embodiment, the bacterial species is selected from the groupconsisting of gram-positive and gram-negative bacteria. In anembodiment, the term can be manifested as microbicidal or microbistaticinhibition of microbial growth.

The term “microorganism” herein refers broadly to bacteria, fungi,viruses, and protozoa. In particular, the term is applicable for amicroorganism having a cellular or structural component of a lipidbilayer membrane. In specific embodiments, the membrane is a cytoplasmicmembrane. Pathogenic bacteria, fungi, viruses, and protozoa as known inthe art are generally encompassed. Bacteria can include gram-negativeand gram-positive bacteria in addition to organisms classified in ordersof the class Mollicutes and the like, such as species of the Mycoplasmaand Acholeplasma genera. Specific examples of potentially sensitivegram-negative bacteria include, but are not limited to, Escherichiacoli, Pseudomonas aeruginosa, Salmonella, Hemophilus influenza,Neisseria, Vibrio cholerae, Vibrio parahaemolyticus and Helicobacterpylori. Examples of potentially sensitive gram-positive bacteriainclude, but are not limited to, Staphylococcus aureus, Staphylococcusepidermis, Streptococcus agalactiae, Group A streptococcus,Streptococcus pyogenes, Enterococcus faecalis, Group B gram positivestreptococcus, Corynebacterium xerosis, and Listeria monocytogenes.Examples of potentially sensitive fungi include yeasts such as Candidaalbicans. Examples of potentially sensitive viruses include measlesvirus, herpes simplex virus (HSV-1 and -2), herpes family members (HIV,hepatitis C, vesicular, stomatitis virus (VSV), visna virus, andcytomegalovirus (CMV). Examples of potentially sensitive protozoainclude Giardia.

The term “hydrophobic amino acid” has a meaning of Tryptophan (W) andany amino acid more hydrophobic than Threonine (T) on the hydrophobicityscale of Kyte and Doolittle (Kyte and Doolittle, J. Mol. Biol.,157(1):105-132 (1982)). Such hydrophobic amino acids include A, V, I, L,W, F, M, G, and C.

The term “cationic amino acid” is intended to mean an amino acid whichhas a net positive charge within the pH range of from about 4 to about12. Cationic amino acids include amino acids K, R, and H.

The term “polar amino acid” includes amino acids S, T, N, and Q.

The term “hydrophilic amino acid” includes any amino acid from thepreviously defines set of cationic and polar amino acids. Suchhydrophilic amino acids include amino acids K, R, H, S, T, N, and Q.

The term “amphipathic” is intended to mean the distribution ofhydrophilic and hydrophobic amino acid residues along opposing faces ofan alpha helix structure, beta strand, linear, circular, or othersecondary conformation, which results in one face of the molecule beingpredominantly hydrophilic and/or charged and the other face beingpredominantly hydrophobic. The degree of amphipathicity of a peptide canbe assessed by plotting the sequence of amino acid residues by variousweb-based algorithms, e.g., those found onus.expasy.org/cgi-bin/protscale.pl. The distribution of hydrophobicresidues can be visualized by helical wheel diagrams. Secondarystructure prediction algorithms, such as GORIV can be found atwww.expasy.com.

The step of determining most common length of the anti-microbialpeptides within the set involves calculating average of all peptidelengths in the database, wherein the peptides in the database are knownto have inhibitory activity against a chosen microbe. The process ofdetermining most common length of the anti-microbial peptide alsoinvolves plotting the peptide lengths to look for features such as abimodal distribution. In the case of a bimodal distribution, the averageof a single mode may be selected with a preference for the mode ofshorter length.

The step of determining most common net charge of the anti-microbialpeptides within the set involves calculating the charge of each peptidein the database, then dividing it by the peptide length. These chargesare plotted to assess distribution and then averaged to determine a mostcommon charge per unit length for the set.

The step of determining most common range of hydrophobicity of theanti-microbial peptides within the set involves calculating the numberof hydrophobic residues in each peptide in the database and thendividing this number by the peptide length. This number is plotted toassess distribution and then averaged to determine a most number ofhydrophobic residues per unit length for the set.

The step of determining most common amino acids of the anti-microbialpeptides within the set involves calculating the total number of timeseach amino acid appears in the database. These amino acids are arrangedinto three categories: hydrophobic, cationic, and all other. The aminoacids with the highest numbers of appearance in each category areconsidered to be the most common for that category.

The step of determining at least one common motif present in theanti-microbial peptides within the set involves identifying a commonlyappearing sequence fragment or identifying a commonly appearing locationof a hydrophobic, cationic, or other amino acid(s) in the peptideswithin the set. For example, we looked at the percentage of peptides inthe database that contained a cationic residue at one terminus and ahydrophobic residue at the other terminus compared to peptides with ahydrophobic residue at both termini or a cationic residue at bothtermini.

The term “helical wheel diagram” means any type of plot or visualrepresentation used to illustrate the properties of alpha helices inproteins and peptides. Typically, the sequence of amino acids that makeup a helical region of the protein's secondary structure are plotted ina rotating manner where the angle of rotation between consecutive aminoacids is 100.degree., so that the final representation looks down thehelical axis.

The term “hydrophobic face” means an area of the peptide surface thatcontains three or more hydrophobic residues in direct proximity.Proximity is determined by being within one or two positions of eachother on a helical wheel diagram, where the entire set of hydrophobicamino acids can be interrupted by no more than two cationic or polaramino acids. Such interruption is referred to here as a hydrophobic faceinterruption.

The term “hydrophilic face” means an area of the peptide surface thatcontains three or more cationic amino acids in direct proximity.Proximity is determined by being within one or two positions of eachother on a helical wheel diagram, where the entire set of cationic aminoacids can be interrupted by no more than two hydrophobic or polarresidues. Such interruption is referred to here as a hydrophilic faceinterruption.

The terms “methods of treating or preventing” mean amelioration,prevention or relief from the symptoms and/or effects associated with amicrobial infection. The term “preventing” as used herein refers toadministering a medicament beforehand to forestall or obtund an acuteepisode. The person of ordinary skill in the medical art (to which thepresent method claims are directed) recognizes that the term “prevent”is not an absolute term. In the medical art it is understood to refer tothe prophylactic administration of a drug to substantially diminish thelikelihood or seriousness of a condition, and this is the sense intendedin applicants' claims. As used herein, reference to “treatment” of asubject is intended to include prophylaxis.

The term “isolated” is not meant to exclude artificial or syntheticmixtures with other compounds or materials, or the presence ofimpurities that do not interfere with the fundamental activity, and thatmay be present, for example, due to incomplete purification, or theaddition of stabilizers.

The peptides of the invention may be substantially pure. The term“substantially pure” refers to a preparation comprising at least 50-60%by weight of the peptide. More preferably, the preparation comprises atleast 75% by weight, and most preferably 90-95% or more by weight of thepeptide. Purity is measured by the appropriate methods (e.g., massspectroscopy, reverse phase-high pressure liquid chromatography, and thelike).

Additionally the peptides of the invention may be operably linked toother known antimicrobial peptides or other substances, such otherpeptides, proteins, oligosaccharides, polysaccharides, other organiccompounds, or inorganic substances. For example the antimicrobialpeptides may be coupled to a substance which protect the antimicrobialpeptides from being degraded within a mammal prior to the antimicrobialpeptides has inhibited, prevented or destroyed the life of themicroorganism.

In an embodiment of the invention, in vitro antimicrobial activity ofthese peptides demonstrated herein is an accurate predictor of in vivoantimicrobial activity.

Pharmaceutical compositions contain a therapeutically effective amountof one or more of the antimicrobial peptides and a suitable carrier. Atherapeutically effective amount of an antimicrobial peptide can bereadily determined according to methods well known in the art. Forexample, the amount will vary depending on the severity of an infection,subject parameters such as the age and the size/weight of a subject withan actual or potential infection of a given microorganism, and the routeof administration and the like.

The present invention relates to compositions comprising one or moreantimicrobial peptides of the invention in a microbicidal effectiveamount and a pharmaceutically acceptable carrier. Such compositions mayadditionally comprise a detergent. The addition of a detergent to suchpeptide compositions is useful to enhance antibacterial characteristicsof the peptides. Although any suitable detergent may be used, thepresently preferred detergent is a nonionic detergent such as Tween 20or 1% NP40. Such antimicrobial pharmaceutical compositions can beformulated and administered in ways, as understood in the art for uselocal or systemic injection, for oral or topical application. In anembodiment, the antimicrobial peptides of the present invention cancomprise from 0.0001% to 50% by weight of such compositions.

It will be understood that a composition for application, e.g., bysystemic injection, will contain an antimicrobial peptide in atherapeutically effective amount or a therapeutically effective amountof an antimicrobial peptide can be conjugated to another molecule withspecificity for the target cell type. The other molecule can be anantibody, ligand, receptor, or other recognition molecule. In anembodiment, the choice of the peptide is made with consideration ofimmunogenicity and toxicity for an actually or potentially infectedhost, effective dose of the peptide, and the sensitivity of the targetmicrobe to the peptide, as known in the art.

In an embodiment, the method of inhibiting the growth of bacteria usingthe peptides of the invention may further include the addition of one ormore other antimicrobial agents (e.g., a conventional antibiotic) forcombination or synergistic therapy. The appropriate amount of thepeptide administered will typically depend on the susceptibility of abacterium such as whether the bacterium is Gram negative or Grampositive, and will be easily discernable by one of ordinary skill in theart.

In an embodiment the invention also provides a composition thatcomprises the peptide, in an amount effective to kill a microorganism,and a suitable carrier. Such compositions may be used in numerous waysto combat microorganisms, for example in household or laboratoryantimicrobial formulations using carriers well known in the art.

Where the peptides are to be used as antimicrobial agents, they can beformulated, for example, in buffered aqueous media containing a varietyof salts and buffers. Examples of the salts include, but are not limitedto, halides, phosphates and sulfates, e.g., sodium chloride, potassiumchloride or sodium sulfate. Various buffers may be used, such ascitrate, phosphate, HEPES, Tris or the like to the extent that suchbuffers are physiologically acceptable to the host that is beingtreated.

Various excipients or other additives may be used, where the peptidesare formulated as lyophilized powders, for subsequent use in solution.The excipients may include various polyols, inert powders or otherextenders.

“Therapeutically effective” as used herein, refers to an amount offormulation, composition, or reagent, optionally in a pharmaceuticallyacceptable carrier, that is of sufficient quantity to ameliorate thestate of the subject, such as human patient or animal, so treated.“Ameliorate” refers to a lessening of the detrimental effect of thedisease state or disorder in the recipient of the therapy. In anembodiment, a peptide of the invention is administered to a subject inneed of treatment.

Pharmaceutically acceptable carrier preparations for administrationinclude sterile or aqueous or nonaqueous solutions, suspensions, andemulsions. Examples of nonaqueous solvents are propylene glycol,polyethylene glycol, vegetable oils such as olive oil, and injectableorganic esters such as ethyl oleate. Aqueous carriers include water,alcoholic/aqueous solutions, emulsions or suspensions, including salineand buffered media. Parenteral vehicles include sodium chloridesolutions, Ringer's dextrose, dextrose and sodium chloride, lactatedRinger's, or fixed oils. Active therapeutic ingredients are often mixedwith excipients that are pharmaceutically acceptable and compatible withthe active ingredients. Suitable excipients include water, saline,dextrose, glycerol and ethanol, or combinations thereof. Intravenousvehicles include fluid and nutrient replenishers, electrolytereplenishers, such as those based on Ringer's dextrose, and the like.Preservatives and other additives may also be present such as, forexample, antioxidants, chelating agents, and inert gases and the like.The actual dosage of the peptides, formulations or compositionscontaining such peptides can depend on many factors, including thesize/weight, age, and health of an organism, however, one of ordinaryskill in the art can use the following teachings and others known in theart describing the methods and techniques for determining clinicaldosages (Spiker B., Guide to Clinical Studies and Developing Protocols,Raven Press, Ltd., New York, 1984, pp. 7-13, 54-60; Spiker B., Guide toClinical Trials, Raven Press, Ltd., New York 1991, pp. 93-101; C. Craig.and R. Stitzel, eds., Modern Pharmacology, 2d ed., Little, Brown andCo., Boston, 1986, pp. 127-133; T. Speight, ed., Avery's Drug Treatment:Principles and Practice of Clinical Pharmacology and Therapeutics, 3ded., Williams and Wilkins, Baltimore, 1987, pp. 50-56; R. Tallarida, R.Raffa and P. McGonigle, Principles in General Pharmacology,Springer-Verlag, new York, 1988, pp. 18-20) to determine the appropriatedosage to use.

In an embodiment, the following dosages are used: generally in the rangeof about 0.001 mg/kg to about 100 mg/kg and preferably from about 0.001mg/kg to about 1 mg/kg final concentration are administered per day toan adult in any pharmaceutically acceptable carrier.

In another embodiment, the present invention may be used as a foodpreservative or in treating food products to control, reduce, oreliminate potential pathogens or contaminants. A peptide of theinvention may be used as a disinfectant, for use in or with any productthat must remain microbial free or be within certain tolerances. In anembodiment, treatment with a peptide provides at least partialregulation of infection or contamination.

In an embodiment it is also possible to incorporate or distribute thepeptides within materials, on devices, or on objects (e.g., on anaccessible surface), where microbial growth or viable presence isundesirable, as a method of microbicidal or microbistatic inhibition ofmicrobial growth by administering to the devices or objects amicrobicidal or microbistatic effective amount of peptide. In anembodiment, such devices or objects include, but are not limited to,linens, cloth, plastics, latex fabrics, natural rubbers, implantabledevices, surfaces, or storage containers.

In an embodiment, the invention provides a method of disinfecting asurface of an article, said method comprising the step of applying tosaid surface an effective amount of a composition comprising at leastone peptide of the invention. In an embodiment, the invention provides adisinfecting solution comprising at least one peptide of the inventionand optionally an acceptable carrier.

Throughout this application, various references are referred to. Thedisclosures of these publications in their entireties are herebyincorporated by reference as if written herein.

The term “mammal” is used in its dictionary sense. Humans are includedin the group of mammals, and humans would be the preferred subjects.

Additionally the invention relates to antimicrobial/pharmaceuticalcompositions comprising at least one peptide of the invention and apharmaceutical acceptable buffer, diluent, carrier, adjuvant orexcipient. Additional compounds may be included in the compositions.These include, for example, chelating agents such as EDTA, EGTA orglutathione. The antimicrobial/pharmaceutical compositions may beprepared in a manner known in the art that is sufficiently storagestable and suitable for administration to humans and animals. Thepharmaceutical compositions may be lyophilized, e.g., through freezedrying, spray drying or spray cooling.

“Pharmaceutically acceptable” means a non-toxic material that does notinterfere with the effectiveness of the biological activity of theactive ingredients, i.e., the peptide(s) of the invention. Suchpharmaceutically acceptable buffers, carriers or excipients arewell-known in the art (see Remington's Pharmaceutical Sciences, 18thedition, A. R Gennaro, Ed., Mack Publishing Company (1990) and handbookof Pharmaceutical Excipients, 3rd edition, A. Kibbe, Ed., PharmaceuticalPress (2000).

The term “buffer” is intended to mean an aqueous solution containing anacid-base mixture with the purpose of stabilising pH. Examples ofbuffers are Trizma, Bicine, Tricine, MOPS, MOPSO, MOBS, Tris, Hepes,HEPBS, IVIES, phosphate, carbonate, acetate, citrate, glycolate,lactate, borate, ACES, ADA, tartrate, AMP, AMPD, AMPSO, BES, CABS,cacodylate, CHES, DIPSO, EPPS, ethanolamine, glycine, HEPPSO, imidazole,imidazolelactic acid, PIPES, SSC, SSPE, POPSO, TAPS, TABS, TAPSO, TES,tricine.

The term “diluent” is intended to mean an aqueous or non-aqueoussolution with the purpose of diluting the peptide in the pharmaceuticalpreparation. The diluent may be one or more of saline, water,polyethylene glycol, propylene glycol, ethanol or oils (such assafflower oil, corn oil, peanut oil, cottonseed oil or sesame oil).

The term “adjuvant” is intended to mean any compound added to theformulation to increase the biological effect of the peptide. Theadjuvant may be one or more of zinc, copper or silver salts withdifferent anions, for example, but not limited to fluoride, chloride,bromide, iodide, tiocyanate, sulfite, hydroxide, phosphate, carbonate,lactate, glycholate, citrate, borate, tartrate, and acetates ofdifferent acyl composition.

The excipient may be one or more of carbohydrates, polymers, lipids andminerals. Examples of carbohydrates include lactose, sucrose, mannitol,and cyclodextrines, which are added to the composition, e.g., forfacilitating lyophilization. Examples of polymers are starch, celluloseethers, cellulose carboxymethylcellulose, alginates, carageenans,hyaluronic acid, polyacrylic acid, polysulphonate,polyethylenglycol/polyethylene oxide, polyvinylalcohol/polyvinylacetateof different degree of hydrolysis, and polyvinylpyrrolidone, all ofdifferent molecular weight, which are added to the composition, e.g.,for viscosity control, for achieving bioadhesion, or for protecting thelipid from chemical and proteolytic degradation. Examples of lipids arefatty acids, phospholipids, mono-, di-, and triglycerides, ceramides,sphingolipids and glycolipids, all of different acyl chain length andsaturation, egg lecithin, soy lecithin, hydrogenated egg and soylecithin, which are added to the composition for reasons similar tothose for polymers. Examples of minerals are talc, magnesium oxide, zincoxide and titanium oxide, which are added to the composition to obtainbenefits such as reduction of liquid accumulation or advantageouspigment properties.

The characteristics of the carrier are dependent on the route ofadministration. One route of administration is topical administration.For example, for topical administrations, a preferred carrier is anemulsified cream comprising the active peptide, but other commoncarriers such as certain petrolatum/mineral-based and vegetable-basedointments can be used, as well as polymer gels, liquid crystallinephases and microemulsions.

The antimicrobial/pharmaceutical compositions may comprise one or morepeptides, such as 1, 2, 3 or 4 different peptides in theantimicrobial/pharmaceutical compositions. By using a combination ofdifferent peptides the antimicrobial effect may be increased as well asdecrease of the possibility that the microorganism to combat might beresistant and/or tolerant against the antimicrobial agent.

Histidin rich and/or kininogen based peptides, particularly as shortpeptides have limited antimicrobial activity. However if these peptidesare in a composition comprising a salt and/or a pH from about 5.0 toabout 7.0, the peptides become active, i.e., an enhanced effect isobtained by the addition of a salt and/or a choice of a specific pHrange.

The peptide as a salt may be an acid adduct with inorganic acids, suchas hydrochloric acid, sulfuric acid, nitric acid, hydrobromic acid,phosphoric acid, perchloric acid, thiocyanic acid, boric acid etc. orwith organic acid such as formic acid, acetic acid, haloacetic acid,propionic acid, glycolic acid, citric acid, tartaric acid, succinicacid, gluconic acid, lactic acid, malonic acid, fumaric acid,anthranilic acid, benzoic acid, cinnamic acid, p-toluenesulfonic acid,naphthalenesulfonic acid, sulfanilic acid etc. Inorganic salts such asmonovalent sodium, potassium or divalent zinc, magnesium, coppercalcium, all with a corresponding anion, may be added to improve thebiological activity of the antimicrobial composition. An antimicrobialH-rich peptides based on kininogen and histidine-rich glycoprotein maybe used in defined solutions, such as gel, where the pH is defined andcontrolled (e.g., pH 5.5-6.0) to enhance the effects of the addedantimicrobial peptides. For example a gel, ointment or bandage, with adefined pH from about 5.0 to about 7.0, such as from about 5.5 to about6.0 with or without an ionic environment will enhance, control, andlocalise the function of the antimicrobial peptides.

The antimicrobial/pharmaceutical compositions of the invention may alsobe in the form of a liposome in which the peptide is combined, inaddition to other pharmaceutically acceptable carriers, with amphipathicagents such as lipids, which exist in aggregated forms as micelles,insoluble monolayers and liquid crystals. Suitable lipids for liposomalformulation include, without limitation, monoglycerides, diglycerides,sulfatides, lysolecithin, phospholipids, saponin, bile acids, and thelike. Preparation of such liposomal formulations is can be found in forexample U.S. Pat. No. 4,235,871.

The antimicrobial/pharmaceutical compositions of the invention may alsobe in the form of biodegradable microspheres. Aliphatic polyesters, suchas poly(lactic acid) (PLA), poly(glycolic acid) (PGA), copolymers of PLAand PGA (PLGA) or poly(carprolactone) (PCL), and polyanhydrides havebeen widely used as biodegradable polymers in the production ofmicrospheres. Preparations of such microspheres can be found in U.S.Pat. No. 5,851,451 and in EP0213303.

Alternatively, the antimicrobial peptides may be dissolved in saline,water, polyethylene glycol, propylene glycol, ethanol or oils (such assafflower oil, corn oil, peanut oil, cottonseed oil or sesame oil),tragacanth gum, and/or various buffers. The pharmaceutical compositionmay also include ions and a defined pH for potentiation of action ofantimicrobial peptides.

The antimicrobial/pharmaceutical compositions may be subjected toconventional pharmaceutical operations such as sterilisation and/or maycontain conventional adjuvants such as preservatives, stabilisers,wetting agents, emulsifiers, buffers, fillers, etc., e.g., as disclosedelsewhere herein.

The antimicrobial/pharmaceutical compositions according to the inventionmay be administered locally or systemically. Routes of administrationinclude topical, ocular, nasal, pulmonar, buccal, parenteral(intravenous, subcutaneous, and intramuscular), oral, parenteral,vaginal and rectal. Also administration from implants is possible.Suitable antimicrobial preparation forms are, for example granules,powders, tablets, coated tablets, (micro) capsules, suppositories,syrups, emulsions, microemulsions, defined as optically isotropicthermodynamically stable systems consisting of water, oil andsurfactant, liquid crystalline phases, defined as systems characterizedby long-range order but short-range disorder (examples include lamellar,hexagonal and cubic phases, either water- or oil continuous), or theirdispersed counterparts, gels, ointments, dispersions, suspensions,creams, aerosols, droples or injectable solution in ampule form and alsopreparations with protracted release of active compounds, in whosepreparation excipients, diluents, adjuvants or carriers are customarilyused as described above. The pharmaceutical composition may also beprovided in bandages or plasters or the like.

The pharmaceutical compositions will be administered to a patient in apharmaceutically effective dose. By “pharmaceutically effective dose” ismeant a dose that is sufficient to produce the desired effects inrelation to the condition for which it is administered. The exact doseis dependent on the, activity of the compound, manner of administration,nature and severity of the disorder, age and body weight of the patientdifferent doses may be needed. The administration of the dose can becarried out both by single administration in the form of an individualdose unit or else several smaller dose units and also by multipleadministration of subdivided doses at specific intervals

The pharmaceutical compositions of the invention may be administeredalone or in combination with other therapeutic agents, such asantibiotic or antiseptic agents such as anti-bacterial agents,anti-fuingicides, anti-viral agents, and anti-parasitic agents. Examplesare penicillins, cephalosporins, carbacephems, cephamycins, carbapenems,monobactams, aminoglycosides, glycopeptides, quinolones, tetracyclines,macrolides, and fluoroquinolones. Antiseptic agents include iodine,silver, copper, clorhexidine, polyhexanide and other biguanides,chitosan, acetic acid, and hydrogen peroxide. These agents may beincorporated as part of the same pharmaceutical composition or may beadministered separately.

The present invention concerns both humans and other mammal such ashorses, dogs, cats, cows, pigs, camels, among others. Thus the methodsare applicable to both human therapy and veterinary applications. Theobjects, suitable for such treatment may be identified bywell-established hallmarks of an infection, such as fever, puls, cultureof organisms, and the like. Infections that may be treated with theantimicrobial peptides include those caused by or due to microorganisms.Examples of microorganisms include bacteria (e.g., Gram-positive,Gram-negative), fungi, (e.g., yeast and molds), parasites (e.g.,protozoans, nematodes, cestodes and trematodes), viruses, and prions.Specific organisms in these classes are well known (see for example,Davis et al., Microbiology, 3.sup.rd edition, Harper & Row, 1980).Infections include, but are not limited to, chronic skin ulcers,infected acute wounds and burn wounds, infected skin eczema, impetigo,atopic dermatitis, acne, external otitis, vaginal infections, seborrhoicdermatitis, oral infections and parodontitis, candidal intertrigo,conjunctivitis and other eye infections, and pneumonia.

The antimicrobial/pharmaceutical compositions may also be used to incleansing solutions, such as lens disinfectants and storage solutions orused to prevent bacterial infection in association with urinary catheteruse or use of central venous catheters.

Additionally the antimicrobial compositions may be used for preventionof infection post-surgery in plasters, adhesives, sutures, or beincorporated in wound dressings.

The antimicrobial peptides may also be used in polymers, textiles or thelike to create antibacterial surfaces or Cosmetics, and personal careproducts (soap, shampoos, tooth paste, anti-acne, suncreams, tampons,diapers, etc) may be supplemented with the antimicrobial/pharmaceuticalcompositions.

The following specific non-limiting examples are illustrative of theinvention.

Example 1 Bioinformatics and Design

Antimicrobial peptides were designed against M. tuberculosis. The designwas based on a published database filtering method (Mishra and Wang, J.Am. Chem. Soc., 134(30):12426-12429 (2012)), a method which outputs themost common peptide length and amino acid composition based on a libraryof natural and synthetic peptides. It is assumed that if this library isselected to include peptides with high potency against a pathogen ofchoice, the resulting composition will also have antimicrobial activity.We designed our novel peptides by ordering the resulting amino acidsusing additional bioinformatic techniques, and using a structurallyinformed approach. A database was created using natural peptides fromdatabanks (APD2, CAMP) and both natural and synthetic peptides reportedin the literature (Ramon-Garcia, et al., Antimicrob. Agents Chemother.,57(5):2295-2303 (2013), Linde, et al., J. Antimicrob. Chemother.,47(5):575-580 (2001), Miyakawa, et al., Infect. Immun., 64(3):926-932(1996), Jiang, et al., Protein Peptide Letters, 18(3): 241-252 (2011))that have measured activity against M. tuberculosis. The database wasthen analyzed to determine average peptide length, number of hydrophobicresidues, number of hydrophilic residues per length, and the mostrepresented residues of each type (FIG. 1), resulting in a definedlength and amino acid composition.

Diverging from the database filtering method, which usesbioinformatic-derived sequence motifs for amino acid order, we designedpeptides by fitting this set of residues to an alpha helical template(helical wheel diagram) to produce several amphipathic peptides (FIG.2). The actual conformation for each designed peptide was predictedusing PepFold (Thevenet, Shen, et al., Nucleic Acids Res. 40 (Web Serverissue):W288-293 (2012)) and the three-dimensional structure of peptideswere modeled using the software Molecular Operating Environment (“MOE,”Chemical Computing Group, Montreal, Canada).

Results

A database of 44 peptides was generated from databank and literaturesources and analyzed using the database filtering method describedabove. The database contained both natural, broadly active AMPs andsynthetic AMPs screened specifically against tuberculosis, providing abreadth of coverage. The average length of the peptides was found to be13 amino acids and this length was chosen for our designed peptide. Thedatabase showed a distinctly bimodal distribution with a group around 12amino acids (mostly the synthetic peptides) and another group around 26amino acids (mostly the natural peptides). Interestingly, these valuescorrespond to the approximate length of 13 amino acids of an alphahelical peptide needed to span half a bacterial membrane and to theapproximate length of 26 amino acid needed to span an entire bacterialmembrane. This observation provides an indication that spanning half themembrane may be sufficient for disruption.

The second parameter analyzed was average charge, which was determinedto be +5. All peptides in the database were cationic. When normalized tothe length of the peptide, the average charge per amino acid was foundto 0.4, a value that was highly consistent across all peptides in thedatabase. Applying this ratio to our novel peptides of 13 amino acidsimplied that 5 of the residues had to be positively charged.

The average number of hydrophobic residues (A, V, I, L, W, F, M, C) wasdetermined to be 6.5 for the selected peptides. Normalization to thelength of each peptide resulted in an average value of 0.5 hydrophobicresidues per number of total residues. Applying this value to ourpeptide of length 13 amino acids suggested a total of 6.5 hydrophobicresidues, which was rounded to 7.

Twelve of the thirteen residues were determined to be charged orhydrophobic, leaving one uncharged, non-hydrophobic residue. Thus, wedetermined that our peptide should contain 5 cationic (K, R, or H), 7hydrophobic residues (A, V, I, L, W, F, M, G, or C), and 1 uncharged,non-hydrophobic residue (S, T, Y, P, N, or Q).

To select the identity of the cationic residues, the frequency of eachresidue in the database was analyzed. All peptides in the databasecontained K, R, or a combination of the two. In contrast, only threepeptides in the entire database were found to contain H, so this residuewas eliminated. For peptides containing R or K, 20% contained only R,14% contained only K, and 66% contained both. As a result a mixture of Kand R was selected, and of our five cationic residues, three wereselected to be K and two were selected to be R.

A similar procedure was followed for hydrophobic residues. A, M, G, andC residues appeared infrequently and were not considered for thisreason. Of the remaining five possible hydrophobic residues, W and Lappeared most frequently, especially among the subset of peptidesapproximately 13 amino acids in length. I was also relatively frequent.Thus, four of the seven hydrophobic residues were selected to be W, twoof the seven were selected to be L, and one of the seven was selected tobe I.

Of the polar residues T, Y, N, and Q appeared infrequently. S appearedmore frequently than P and S also better supports an alpha helicalconformation. Thus, the final residue was selected to be S.

The overall output of database filtering against tuberculosis resultedin a peptide length of 13 amino acids, containing two R, three K, fourTrp, two L, one I, and one S amino acid. Peptide sequences weredetermined by arranging the selected above set of amino acids in anamphipathic manner on a helical wheel diagram. This arrangement wasadditionally constrained to have a cationic residue at one terminus, acommon motif observation from the database. In total, we developed threenovel candidate peptides having the following sequences:

Peptide B1 sequence: (SEQ ID NO: 1) ILSLRWRWKWWKK; Peptide B2 sequence:(SEQ ID NO: 2) ILSLRWWRKWWKK; and Peptide B3 sequence: (SEQ ID NO: 3)ILSLRWRWWKWKK.

Peptide B1 contains two hydrophobic faces with one hydrophobic faceinterrupted by a cationic amino acid K, peptide B2 contains a singlelarge hydrophobic face interrupted by uncharged S, and peptide B3contains a large hydrophobic face interrupted by cationic amino acids Rand K (FIG. 2). An alpha helical conformation for each peptide waspredicted using PepFold and MOB software.

We also designed and tested a scrambled peptide B4, having the followingsequence:

Peptide B4 sequence: (SEQ ID NO: 4) IRKLKSWKWLRWL.

The amino acids of the scrambled peptide B4 are the same as those inpeptides B1, B2, and B3. However, the sequence of these amino acids inthe scrambled peptide B4 was not guided by any rational designparameter.

Example 2 Peptide Synthesis and Purification

Peptides B1, B2, B3, and B4 were synthesized using an automatedsynthesizer (Multipep RS, Intavis Inc., Germany). Fmoc solid-phasechemistry was used to synthesize the peptides from their C-termini toN-termini on a TentaGel rink amide resin (0.25 mmol/g) (Intavis Inc.).Pre-synthesis, the resin was swollen in a DMF:DCM (2:1) solution.Post-synthesis, the resin was washed with DCM and the peptides werecleaved off using TFA/TIS/H2O (88/6/6) cocktail. Bulk TFA was removed byprecipitating the peptides in ice-cold MTBE followed by centrifugationand a second MTBE wash. Peptides were air-dried and dissolved in ACN:H2O(1:5) for lyophilization. Lyophilized peptides were stored at−20.degree. C. Peptides were purified using a Waters HPLC (WatersCorporation, Milford, Mass.) with a C18 column (XBridge™ BEH130 C18Column, Part #: 186003568, Waters Corporation). Isocratic elution wasperformed at 30% acetonitrile at 50.degree. C. Peptide purity increasedfrom <50% to >90%.

Example 3

Determination of Peptide Structure by Far-Ultraviolet Circular Dichroism

Lipid films were prepared by dissolving 11.25 μmoles POPC(1-Palmitoyl-2-Oleoyl-sn-glycero-3-phosphocholine) and 3.75 μmoles POPG(1-Palmitoyl-2-Oleoyl-sn-glycero-3-phosphoglycerate) in chloroform intoa round bottom flask. Chloroform was evaporated under gentle N₂ flow for10 min, and lyophilized overnight to ensure complete evaporation. Lipidfilm was rehydrated with 3 mls 10 mM PB buffer at pH 7.4. Threefreeze/thaw cycles were performed followed by a 31 pass extrusion usinga 200 nm membrane at 45° C. The peptides were dissolved in 10 mM PBbuffer at pH 7.4 to a concentration of 500 μM peptide. The peptides andlipids were brought to a final mole ratio of 1:10 AMP:lipid with a finalconcentration of 50 μM AMP. Spectra were collected using a Jasco 815 CDSpectrometer (Jasco, Easton, Md.) with a Spectrosil® Far UV Quartzcuvette (Starna Cells Inc., Atascadero, Calif., Cat #: 21-Q-1).Measurements were taken at 21° C. using 10 accumulations. Spectra wereread from 260 to 190 nm with a 1.0 nm band width, a sensitivity of 100mdeg, a response of 1 s, and a scan speed of 100 nm/min. Afterbackground subtraction, mean residual elipticity (Θ) was reported as afunction of wavelength.

Results

To gain insight into the secondary structure of the designed peptides,Far-Ultraviolet Circular Dichroism (“far-UV CD”) was performed with thepeptides in PB buffer and in the presence of bacterial mimetic lipidvesicles (POPC:POPG 3:1 mole ratio). In PB buffer, peptides B1, B2 andB3 produced far-UV CD spectra associated with alpha-helical peptides,with 0 minima at 222 nm and 205 nm in addition to an apparent maximum at190 nm (Blondelle, Lohner, et al., Biochimica et Biophysica Acta(BBA)-Biomembranes, 1462(1):89-108 (1999); Campagna, Saint, et al.,Biochemistry, 46(7):1771-1778 (2007)). The scrambled sequence B4 peptidemaintained a spectrum more closely aligned with random coil/extendedstructure with a single minimum at 200 nm (Greenfield, Nature protocols,1(6):2527-2535 (2006)).

In the presence of PC:PG lipid vesicles, B1 and B3 peptides retainedtheir alpha-helical structure with characteristically similar spectra tothose in PB buffer. B2 and B4 peptides had completely unique spectrawhen PC:PG vesicles were present. The B2 peptide spectrum contained anaccentuated local maximum at 232 nm, a global minimum at 222 nm, ashoulder at 207 nm, and global max at 190 nm. Conversely, B4 peptideresulted in a slightly blue shifted spectrum yet with the same maximabut the minimum and shoulder locations swapped. These spectra containfeatures associated with kinked proline-rich proteins (232 nm max) andhelical proteins (222 nm min, 207 nm shoulder, 190 nm max) indicatingthe presence of kinked helices for both B2 and B4 peptides in thepresence of bacterial mimetic lipid vesicles (Greenfield, Natureprotocols, 1(6): 2527-2535 (2006); Whitmore and Wallace, Biopolymers,89(5): 392-400 2008).

Example 4 Disk Diffusion Assays

Disk diffusion assays were performed with M. tuberculosis mc² 6020 andM. smegmatis on 7H10 agar plates supplemented with glycerol, OADC,pantothenate and lysine as described in Sambandamurthy, et al., 2006.Vaccine, 24:6309-6320 (2006). 100 μL of a 0.25 OD600 culture (2×106bacteria) was spread on the surface of the agar plates prior to additionof 6 mm paper disks impregnated with 100 μg peptide dissolved in water.Control disks included water (negative) or 10 μg kanamycin (positive).Plates were incubated for three weeks at 37° C. All peptides were testedin duplicate. Antibacterial activity was visualized as clear zonesaround disks.

Results

Peptides B1, B2, and B3 showed inhibition against M. tuberculosis mc²6020 and M. smegmatis. Kanamycin, which showed a strong signal, was usedas a positive control while the negative (water) control showed noinhibition. Both peptides B1 and B3 showed better inhibition of M.tuberculosis mc² 6020 and M. smegmatis than peptide B2.

Example 5 Micro-Broth Dilution MIC Determinations

All antimicrobial susceptibility testing was performed in a final volumeof 100 μl in sterile U-shaped 96-well polypropylene microtiter plates.Separate 96-well plates were filled with 100 μl of media broth for thegrowth of different test organisms. Initial AMP (B1 through B4) orgentamicin dilutions (at 512 μg/ml) were prepared and subsequent twofold dilutions were performed in 0.1 ml media broth in the microplates.Non-experimental wells were filled with sterile distilled water toprevent dehydration in experimental wells. M. tuberculosis (MC26230 andMC26020), Mycobacterium smegmatis, or BCG bacteria from frozen stocks,initially diluted to an optical density (OD) of 0.1, were eachpropagated at 37° C./ambient for 7 (M. tuberculosis mc26230, M.smegmatis, and BCG) to 9 days (mc26020) during which they attained a logphase growth. Following propagation, each bacterial culture wassonicated (for a total of 20 s with 5 s continuous pulses and 5 s offperiods, with instrumentation settings at low power), diluted to 0.1 ODbacteria suspension, and a 1:10 dilution was further made forinoculation into the AMP-containing media broth. Five micro liter (5 μl)of the 1:10 diluted bacteria was added to each AMP-containing wells. Awell without any of the AMP agent was also inoculated with 5 μl doublediluted bacteria as a growth control. The plates were wrapped inaluminum foil and incubated at 37° C. for 5 days in a moisturizedincubator. Following incubation, Alamar blue reagent (10 μl) was addedto all experimental wells and further incubated for 24 to 48 hr. A colorchange from blue (inhibition) to pink (no inhibition) was observed andrecorded. Visual MICs were defined as the lowest concentration of MICthat prevented a color change. For non-M. tuberculosis screening, freshovernight cultures of selected gram positive bacteria (Staphylococcusaureus ATCC 25923, Enterococcus faecalis ATCC 29212, Streptococcuspneumonia ATCC 49619, Streptococcus pyogens, Streptococcus agalactiae,Streptococcus mutans, and Bacillus subtilis) and gram negative bacteria(Pseudomonas aeruginosa ATCC 27853, Klebsiella pneumoniae 13-329999 g,and Escherichia coli) were subcultured at 37° C./shaking for 3.5 to 4 hrat 200 rpm either in 5 ml Mueller-Hinton (MH; Difco) broth or MH brothsupplemented with 5% sheep red blood cells. Bacteria inoculum wasprepared and then added to 96-well plates containing AMPs as in M.tuberculosis experiments above. The plates OD before and afterincubation were obtained and the difference recorded. MIC was defined asthe lowest drug concentration that exhibited no growth by visualreading.

Results

In Vitro Activity and Toxicity Against M. tuberculosis.

The in vitro activity of the four peptides (B1, B2, B3, and B4) wasmeasured using standard methods including a disk diffusion assay andAlimar blue assay. All three designed peptides were observed to haveantimicrobial properties in the disk diffusion assay, and this activitywas subsequently quantified with the Alimar blue assay. Peptide B3 wasfound to be active against M. tuberculosis MC26020 at MIC values of 8μg/mL. Peptides B1 and B2, as well as the scrambled peptide B4, did notinhibit growth until 32 μg/mL. Considering all four peptides werederived from the same set of amino acids, this result highlights theimportance of pairing database filtering with rational design. Thoughfiltering alone resulted in a set of relatively efficacious amino acids,rational ordering of these residues improved the efficacy of peptide B3an order of magnitude over the scrambled peptide B4.

All four peptides were also found to be active against M. tuberculosisstrain MC26230, but interestingly, the activity of all four peptides wasattenuated. For peptide B3, the MIC was increased from 8 μg/mL to 64μg/mL with the other peptides also showing MIC increases. Additionallythe four peptides inhibited growth against other mycobacteria includingM. smegmatis and BCG at concentrations on the same order as those for M.tuberculosis MC26230. The results of this study are shown in FIG. 3.

In Vitro Activity and Toxicity Against Other Clinically RelevantBacteria

In addition to tuberculosis, the four peptides were tested againstseveral strains of clinically relevant gram-positive and gram-negativebacteria. In general, the peptides were more potent againstgram-positive species than gram-negative species. The peptides wereespecially potent against streptococcus species, with MIC values as lowas 4 μg/mL. The peptides were less efficacious against some microbessuch as E. faecalis with MICs of 512 μg/mL. While consistent withprevious findings that cationic, amphipathic peptides are broadlyactive, the range of potencies highlights the need for species specificdatabase optimization during peptide design.

Interestingly, in most cases against gram-negative bacteria peptide B2was more potent than B3. This was not observed with M. tuberculosis.This result again illustrates the importance of amino acid ordering andindicates that the mechanism of antimicrobial activity may differbetween gram-positive bacteria and tuberculosis, which is neithergram-positive nor-negative. The results of this study are shown in FIGS.4 and 5.

Example 6 Assay for Peptide Cytotoxicity Against Mammalian Cells

Cytotoxicity studies were performed using three mammalian cell lineswhich included mouse macrophage J774.16 cell line, human lung epithelialA549 cell line, and sheep red blood cells (sRBCs) in Trypticase soy agar(TSA). Mouse macrophage J774.16 cell line (maintained in antibiotic-freeDulbecco's modified Eagle's medium containing 20% fetal bovine serum, 5%NCTC 109, 1% nonessential amino acids and 1% glutamine) or human lungepithelial A549 cell line (maintained in antibiotic-free Ham's F12medium supplemented with 10% fetal bovine serum) was seeded at a densityof approximately 1.times.105 cells per ml in Lab-tek Permanoxeight-chamber microscopy slides (Nunc, Inc., Naperville, Ill.) andincubated for 3 (J774.16) or 5 (A549) days before use. After celldifferentiation to a confluence of 70 to 80%, the culture media wasreplaced with fresh media containing the different AMPS at 64 μg/ml orat toxic dose (320 μg/ml) or controls (media only for negative controlor 50 μM NaN3 for positive control). Similarly, AMPS or 1% Triton 100-Xas positive control or media only (negative control) was each added toseparate wells and allowed to be absorbed into agar at room temperature.All experiments were incubated for 24 hr at 37° C., 5% CO2. Allexperiments were done in duplicates. Cytotoxicity for J774.16 or A549cells was monitored using Trypan Blue exclusion assay and the ratio ofdead to viable cells was recorded. For sRBCs, the presence of cell lysisafter 24 hr of incubation at 37.degree. C. following treatment indicatedcytotoxicity. The results of this study are shown in FIG. 6.

Results Cytotoxicity Against Mammalian Cells

To check for cytotoxicity against mammalian cells, the four peptideswere tested against macrophage J774.16 cells, lung epithelial cells, andsheep red blood cells. All peptides tested were non-toxic to mammaliancells at the MICs required for antimicrobial activity. Peptide B3, themost potent antimicrobial peptide, began to show moderate cytotoxicityagainst macrophage J774.16 cells at 320 m/mL, which is at least fivetimes the MIC of this peptide against mycobacteria and streptococci. B3similarly exhibited some degree of cytotoxicity in lung epithelialcells, however, the cytotoxicity level was relatively milder whencompared to that on J774.16 cells. The results of this study are shownin FIG. 6.

The lack of cytotoxicity of our novel peptides is likely due to thedesigned inclusion of at least one cationic residue within thehydrophobic face, following the imperfect amphipathicity approach ofWimley (Wimley and Hristova, Journal of Membrane Biology, 239(1-2):27-34(2011)). This lack of cytotoxicity is important because to be useful asa broad-spectrum anti-microbial drug, it is necessary to dissociateanti-eukaryotic activity from antimicrobial activity, i.e., increasingthe antimicrobial activity and reducing toxicity to normal cells.

Although the disclosed subject matter has been described and illustratedwith respect to embodiments thereof, it should be understood by thoseskilled in the art that features of the disclosed embodiments can becombined, rearranged, etc., to produce additional embodiments within thescope of the invention, and that various other changes, omissions, andadditions may be made therein and thereto, without parting from thespirit and scope of the present invention.

What is claimed is:
 1. A peptide comprising a sequenceX₁X₂X₃X₄X₅X₆X₇X₈X₉X₁₀X₁₁X₁₂X₁₃ (SEQ ID NO: 6), wherein: X₁, X₂, X₄, X₆,and X₁₁ are each a hydrophobic amino acid, X₁ is selected from the groupconsisting of S, T, N, and Q, X₅, X₁₂, and X₁₃ are each a cationic aminoacid, X₇, X₈, X₉, and X₁₀ are selected from the group consisting of ahydrophobic amino acid and a cationic amino acid, X₇ and X₈ cannot bothbe a hydrophobic amino acid and cannot both be a cationic amino acid, X₉and X₁₀ cannot both be a hydrophobic amino acid and cannot both be acationic amino acid, and one or more of the following: (i) X₇ and X₈ areselected from the group consisting of R and W, wherein X₇ and X₈ are notthe same, (ii) X₉ and X₁₀ are selected from the group consisting of Kand W, wherein X₉ and X₁₀ are not the same, (iii) X₁, X₂, X₄, X₆, andX_(ii) are selected from the group consisting of I, L, and W, and (iv)X₃ is S or T, wherein X₅, X₁₂, and X₁₃ are selected from the groupconsisting K and R.
 2. The peptide according to claim 1, wherein X₃ isS.
 3. The peptide according to claim 1, wherein the peptide includes atleast one D-amino acid.
 4. The peptide according to claim 1, wherein thepeptide includes at least one modification includes amidation,acetylation, halogenation, or combinations thereof.
 5. A compositionincluding at least one peptide of claim 1 and a pharmaceuticallyacceptable buffer, diluent, carrier, adjuvant, or excipient.
 6. Thecomposition according to claim 5, further comprising at least oneantibiotic agent.
 7. The composition according to claim 6, wherein theat least one antibiotic agent is selected from the group consisting ofisoniazid, rifampicin, pyrazinamide, ethambutol, levofloxacin,moxifloxacin, ofloxacin, kanamycin, amikacin, capreomycin, streptomycin,bedaquiline, para-aminosalicyclic acid, para-aminoslicyclic acid,cycloseline, and combinations thereof.
 8. A disinfecting solutionincludes the peptide of claim 1 and an acceptable carrier.
 9. Thepeptide according to claim 1, wherein the peptide includes IRKLKSWKWLRWL(SEQ ID NO: 4).
 10. The peptide according to claim 9, wherein thepeptide includes at least one D-amino acid.
 11. A composition includingat least one peptide of claim 9, and a pharmaceutically acceptablebuffer, diluent, carrier, adjuvant, or excipient.
 12. The compositionaccording to claim 11, further comprising at least one antibiotic agent,wherein the at least one antibiotic agent is selected from the groupconsisting of isoniazid, rifampicin, pyrazinamide, ethambutol,levofloxacin, moxifloxacin, ofloxacin, kanamycin, amikacin, capreomycin,streptomycin, bedaquiline, para-aminosalicyclic acid,para-aminoslicyclic acid, cycloseline, and combinations thereof.
 13. Thepeptide according to claim 9, wherein the peptide includes at least onemodification includes amidation, acetylation, halogenation, orcombinations thereof.
 14. A disinfecting solution includes the peptideof claim 9 and an acceptable carrier.
 15. A method for designing a novelpeptide, the method comprising: (a) identifying a set of anti-microbialpeptides having inhibitory activity against a chosen microbe; (b)determining most common length of the anti-microbial peptides within theset; (c) determining most common net charge of the anti-microbialpeptides within the set; (d) determining most common range ofhydrophobicity of the anti-microbial peptides within the set; (e)determining most common amino acids of the anti-microbial peptideswithin the set, (f) optionally, determining at least one common motifpresent in the anti-microbial peptides within the set, wherein steps (b)through (e) and the optional step (f) are performed sequentially,non-sequentially, or simultaneously; (g) designing an amino acidsequence of the novel peptide by selecting amino acids of the novelpeptide using a helical wheel diagram, wherein the novel peptide has themost common length determined in step (b), has the most common netcharge determined in step (c), has the most common hydrophobicitydetermined in step (d), consists of the most common amino acidsdetermined in step (e), and, optionally, has the at least one commonmotif determined in step (f), wherein the novel peptide has one or morehydrophobic faces and one or more hydrophilic faces as predicted by thehelical wheel diagram, wherein at least one hydrophobic face of the oneor more hydrophobic faces includes at least one hydrophobic faceinterruption, wherein the at least one hydrophobic face interruption ispositioned within the at least one hydrophobic face and consists of oneor two amino acids selected from the group consisting of K, R, H, S, T,N, Q, and combinations thereof; (h) employing a software program togenerate a three dimensional model of the novel peptide having the aminoacid sequence designed in step (g); (i) confirming that the threedimensional model of the novel peptide generated in step (h) has analpha helical structure; (j) confirming that the three dimensional modelof the novel peptide generated in step (h) has the one or morehydrophobic faces and the one or more hydrophilic faces, wherein steps(i) and (j) are performed sequentially, non-sequentially, orsimultaneously; (k) repeating steps (g) through (j) if the threedimensional model generated in step (h) does not have an alpha helicalstructure, does not have the one or more hydrophobic faces, or does nothave the one or more hydrophilic faces.
 16. The method for designing thenovel peptide of claim 15, wherein the amino acid sequence of the novelpeptide has a cationic amino acid at at least one terminus.
 17. Themethod for designing the novel peptide of claim 15, further comprisingsynthesizing the novel peptide.
 18. The method of claim 17, furthercomprising testing the novel peptide for anti-microbial properties. 19.The method of claim 15, wherein the most common length of theanti-microbial peptides within the set is 13 amino acids.
 20. The methodof claim 15, wherein the most common length of the anti-microbialpeptides within the set is 26 amino acids.